Cook spaghetti according to package directions. Drain and set aside.
Heat olive oil in a large skillet; add garlic and onions. Sautee for 5 minutes. Add zucchini and mushrooms. Sautee for an additional 5 minutes. .
In a large bowl, combine pasta, vegetable mixture, and remaining ingredients [except mozzarella cheese]. Transfer to a greased pie dish [mine was 9 inches].
Bake for 20 minutes. Remove from oven and add mozzarella cheese. Bake for an additional 5 minutes until cheese is melted.
Remove from oven and let stand for 5-10 minutes before serving. Cut into wedges or scoop out and serve.
Recipe by Mom to Mom Nutrition at https://momtomomnutrition.com/food-and-recipes/spaghetti-pie/